The invention relates in general to a method and apparatus for coating fabric, such as drapery fabric or the like, with foam to form a backed fabric. In particular, it relates to the method and apparatus for foam coating fabric without any visible "streak" or "hose" marks on the fabric backing.
According to the method of fabric foam-backing most commonly used at present, fluid-foam is formed in a reservoir (otherwise known as a pillow, puddle, or bank) on top of a web of fabric to be backed. The front edge portion of the reservoir is formed by a doctor blade, stationary roller, or the like, which blade or roller has the bottom surface thereof spaced a predetermined distance from the fabric web. As the fabric moves past the foam pillow and doctor blade, a predetermined amount of foam adheres thereto, forming the backing thereof, and additionally causes the foam pillow to "rotate" or "roll" generally about a horizontal axis. The volume of foam in the pillow is replenished by traversing a hose along the top surface thereof, which hose delivers fluid foam to the pillow. Since the pillow is rotating, however, the foam most recently deposited by the hose rotates directly into contact with the fabric web. Since the "new" foam has a slightly different density than the "old" foam volume in the reservoir, streak or hose marks occur on the foam backing, leading to an unsightly appearance. Typical prior art devices for practicing such a method (as applied to carpets rather than fabrics, however) are shown in "Vinyl: a Superior Foam for Carpet Backing", by DeVito and Simoneau, Modern Textiles, Vol. 52, April 1971, pp. 24, 26, 28, and 32, and "Vinyl Finds Huge New Foam Market (Maybe 500 Million Lb. by '75)", by Hall, Modern Plastics, February 1972, pp. 51-53.
It has been suggested that air bubbles in the foam pillow may be prevented by depositing the foam to be added directly into the foam pillow, rather than just on top of it (see "Acrylic Foam Backing: Here's How To", by Abbenheim, Textile Manufacturer, January-February 1972, pp. 43-44). A practical way of accomplishing this without introducing "hose" marks has not -- it is believed -- been suggested, however. If the hose is merely placed directly into the top of the pillow, then the rotation of the pillow therepast will result in the introduction of hose marks which it is an object of the present invention to avoid. Also, problems with side-to-side variations of the foam may result. If the hose is placed into the foam pillow from the top and is reciprocated, then hose marks still remain, and the possibilities of introducing air into the pillow by a "furrow" that will be formed on the rolling surface of the pillow will be greatly enhanced.
According to the teachings of the present invention, a method and apparatus for foam backing of fabric are provided that solve the problem of streak marks being formed on the foam backing by the entrainment of air in the foam pillow, and eliminates hose marks being formed thereon. According to the method of the present invention, fluid foam is introduced into a foam pillow to maintain the volume thereof by directing foam to flow substantially along the axis of rotation of the foam pillow on either side thereof. By "generally along the axis of rotation of the foam pillow" is meant that the form is introduced within the volume of the pillow (i.e. the point of introduction is completely surrounded by the foam of the pillow) and is directed so that it flows initially in a substantially horizontal plane that is substantially parallel to the plane of the fabric web. In this way the introduced foam is completely mixed with the foam already in the pillow, and there are no readily visible lines of demarcation between "old foam" and "new foam" areas. No air is entrained since the new foam is introduced directly into the pillow, and there are no hose marks because there is nothing to obstruct and deform the rotating surface of the pillow as it moves into contact with the fabric web to be deposited thereon.
According to the apparatus of the present invention, two hoses are provided having end portions thereof extending into the foam pillow substantially along the axis of rotation thereof, one hose being provided through a guide plate or side deckle on either side of the foam pillow. Complicated traversing devices of the prior art are eliminated. Only the web and foam need to move -- no other moving parts need be provided.
It is the primary object of the present invention to provide a method and apparatus for foam backing of fabric, such as drapery fabric and the like, that does not leave streak and hose marks in the foam backing. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.